Wang Chen, Li Guang, Cui Hongsen, Ge Yansong, Fu Shiqiang, Guan Hongling, Zhou Shun, Hu Xuzhi, Shao Wenlong, Jia Peng, Chen Guoyi, Du Shengjie, Ke Weijun, Fang Guojia
School of Electronics and Electrical Engineering, Wuhan Textile University, Wuhan, 430200, P. R. China.
Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan, 430072, P. R. China.
Adv Mater. 2025 May 6:e2502450. doi: 10.1002/adma.202502450.
All-perovskite tandem solar cells (TSCs) paired by wide-bandgap (WBG) perovskites with narrow-bandgap perovskites holds the potential to overcome the Shockley-Queisser limitation. However, the severe phase segregation and non-radiative recombination of WBG perovskite put on a shadow for their power conversion efficiency and stability. Here, an interfacial engineering strategy is introduced into the triple-halide WBG perovskite. Potassium trifluoromethanesulfonate (TfOK) is utilized to reconstruct the buried interface of the triple-halide WBG perovskite. The distribution of (chlorine) Cl changes from perovskite bulk toward the buried interface due to the TfOK addition. Therefore, a wider bandgap perovskite thin layer is formed at buried layer, which can form a graded heterojunction with bulk WBG perovskite to improve carrier separation and transfer. Meanwhile, the (potassium) K of TfOK diffuses into WBG perovskite bulk to suppress halide phase segregation. Consequently, the 1.78 eV WBG PSCs deliver an impressive power conversion efficiency of 20.47% and an extremely high fill factor over 85%. Furthermore, the resultant two-terminal all-perovskite TSCs achieves a champion efficiency of 28.30%. This strategy provides a unique avenue to improve performance and photostability of WBG PSCs, a new function of Cl in triple-halide is illustrated.
由宽带隙（WBG）钙钛矿与窄带隙钙钛矿配对的全钙钛矿串联太阳能电池（TSCs）有潜力克服肖克利-奎塞尔极限。然而，WBG钙钛矿严重的相分离和非辐射复合对其功率转换效率和稳定性产生了负面影响。在此，一种界面工程策略被引入到三卤化物WBG钙钛矿中。三氟甲磺酸钾（TfOK）被用于重构三卤化物WBG钙钛矿的掩埋界面。由于添加了TfOK，（氯）Cl的分布从钙钛矿本体向掩埋界面发生变化。因此，在掩埋层形成了一个带隙更宽的钙钛矿薄层，它可以与本体WBG钙钛矿形成渐变异质结以改善载流子的分离和转移。同时，TfOK中的（钾）K扩散到WBG钙钛矿本体中以抑制卤化物相分离。结果，1.78 eV的WBG钙钛矿太阳能电池（PSCs）实现了令人印象深刻的20.47%的功率转换效率和超过85%的极高填充因子。此外，由此得到的两端全钙钛矿TSCs实现了28.30%的最佳效率。该策略为提高WBG PSCs的性能和光稳定性提供了一条独特途径，并阐明了三卤化物中Cl的新功能。
